1. Field
The present invention relates to an organic light-emitting diode (OLED) display device and a method of manufacturing the same.
2. Description of the Related Art
Organic light-emitting diode (OLED) display devices are drawing attention as next-generation display devices due to their wide viewing angle, high contrast, and fast response time. In an OLED display device, an organic light-emitting layer includes an emitting layer between an anode and a cathode. The emitting layer is made of an organic material. When positive and negative voltages are respectively applied to these electrodes (i.e., to the anode and to the cathode), holes move from the anode to the emitting layer via a hole-injection layer and a hole-transporting layer, and electrons move from the cathode to the emitting layer via an electron-injection layer and an electron-transporting layer. The electrons and the holes recombine in the emitting layer to generate excitons. As the excitons change from an excited state to a ground state, the emitting layer emits light. As a result, an image is displayed.
The OLED display device includes a pixel defining layer having an opening that exposes an upper surface of the anode, and the organic light-emitting layer is formed on the anode that is exposed through the opening of the pixel defining layer. The cathode is formed on the organic light-emitting layer and the pixel defining layer.
Some layers of the organic light-emitting layer may be formed by a solution process. The solution process includes preparing a solution composition by mixing an organic material for forming a desired layer with a solvent and ejecting the solution composition into the opening of the pixel defining layer. Here, the pixel defining layer is liquid-repellent, and the anode is lyophilic. Thus, a pinning point of the solution composition may be formed at a certain location in the pixel defining layer. If the pinning point is formed in an upper portion of the pixel defining layer, the hole-injection layer may directly contact the cathode. As such, because the hole-injection layer and the cathode are directly connected to each other without the emitting layer, a leakage current is generated between the hole-injection layer and the cathode.